DESCRIPTION: This population-based epidemiologic study will examine the role that nutritionally-related factors play in the development of endometrial cancer. Special emphasis will be placed on phytoestrogens (i.e., weak estrogens, derived from plant foods, that may have antiestrogenic effects) and physical activity. Little is known about how these factors affect endometrial cancer risk and both offer potential avenues for prevention. Additionally, there are plans to determine whether the effects of obesity, a strong risk factor for endometrial cancer, can be modified by high levels of phytoestrogen consumption. Building on research currently being conducted, there are plans to examine the effects of seven specific phytoestrogenic compounds. The proposed case-control study will be conducted in the San Francisco Bay Area, an ethnically and culturally heterogeneous population, providing substantial variation in dietary intake, including phytoestrogen consumption, and physical activity. White, African American and Latina women, aged 35-79, diagnosed with endometrial cancer during a three-year period, will be identified. These cases will be frequency-matched to controls, based on ethnicity and five-year age group. Controls will be identified from control women, participating in an ongoing, population-based, case-control study of breast cancer, which addresses analogous hypotheses. The questionnaire being used in that study, which was developed specifically to address these areas (including a comprehensive assessment of diet and lifetime occupational and leisure time physical activity), will be used in the proposed study. In-person interviews will be conducted in English or Spanish and anthropometric measurements taken. After initial examination of the data, analyses will be conducted, using unconditional logistic regression, adjusting for age, ethnicity and potential confounders. By combining this research with the ongoing breast cancer study, the proposed study will provide important information on endometrial cancer aetiology and the relationship between breast and endometrial cancer aetiology in terms of these modifiable, nutritionally-related factors.